1. Field of the Invention
The present invention is directed to the field of shell magazines for large guns, such as automatic cannon, and more particularly to linkless, conveyor-type shell magazines.
2. Description of the Prior Art
Many different types of large, rapid-fire or automatic cannon are used by the military in such varied applications as antiaircraft, anti-tank and aircraft armament systems. Because the firing rates of the cannon used in such applications are relatively high, and because of the time required to replenish associated shell magazines, the magazines are usually required to have large shell capacities. At the same time, magazine size and weight are also usually important factors to consider, and so dense shell packing in the magazines is ordinarily necessary. Obviously the magazines must also have the capability for rapidly delivering shells contained therein to a shell feeder associated with the magazine and gun.
According to gun and weapon system configuration, a number of different kinds of shell magazines or supplies have been produced for rapid-fire or automatic guns. Probably the simplest and least expensive shell supply is the belt-type in which shells are held in a side-by-side relationship. Originally, for small calibre weapons, these belts were made of fabric, loops being provided to hold the shells. Many, if not most, modern ammunition belts are of the metal link type, adjacent pairs of individual links being held together by the shells. Consequently, as the shells are extracted from the belt for firing, the belt disintegrates, the loose links typically being discharged and discarded with the fired shell casings.
A disadvantage of linked belt ammunition, particularly for use with large calibre guns, is that the loaded belts, even though usually considered as being flexible, are, in fact, relatively stiff and rigid. As a result, most ammunition belts cannot be tightly accordian folded in a manner providing high shell packing densities. Moreover, because belts of large calibre shells are very heavy when fully loaded, advancing of the belts to and through the associated gun requires a substantial amount of power. If the gun is self-powered, through use of high-pressure barrel gases or firing recoil, use of part of this power to advance the ammunition belt slows operation of the gun.
As an alternative to use of link-belted ammunition storage, some automatic or rapid-fire gun systems use cylindrical ammunition drum magazines in which rows of shells are loaded into a number of pie-shaped segments into which the magazine is divided. Each row of shells may hold 10 to 20 shells and 15 to 20 segments may be provided. The magazine drum is rotated so as to align a selected one of the shell-holding segments with a shell feeder which transfers shells from the selected segment to the associated gun for firing. Exemplary of such drum-type magazines is that disclosed in my prior U.S. Pat. No. 3,683,743.
An important advantage of many such segmented drum magazines is that a variety of different shell types can, if desired, be stored in different shell segments which can be selectively accessed. As an illustration, although most of the segments of the drum associated with an antiaircraft gun system are loaded with high explosive shells, some segments can be loaded with armor-piercing shells to enable the gun to operate in a secondary role as an anti-tank gun.
However, not all gun systems are required to have the dual role capability enabled by many drum-type magazines, and, for such other reasons as magazine space constraints or particular weapon system configuration, other types of shell magazines may be preferred. In particular, endless belt, linkless-type shell magazines are useful in many automatic gun systems, particularly airborne systems. In such linkless magazines, a ladder-like conveyor is looped over a number of guides which constrain the conveyor to a closely-folded, serpentine path within a magazine housing. Typically the conveyor has a bicycle chain-type configuration with the guides being correspondingly sprocket shaped. Shells are freely contained in the conveyor, between projecting pins or "rungs", and are confirned therein by dividing walls within the housing. One or more of the sprocket-shaped conveyor guides is driven, for example, by an electric or air motor, in a manner causing the conveyor to move shells towards a position from which they are extracted from the conveyor by a shell feeder. Because of the closely folded configurations of the conveyor, high shell packing densities can usually be achieved in such magazines.
Some gun system applications also require that fired shell casings be stored rather than be ejected from the system, as is a common practice. In particular, some airborne gun systems require the storing of fired shell casings so as to avoid the potential hazard to following, friendly aircraft posed by casings ejected from the aircraft. For this reason, at least some linkless-type shell magazines and associated feeders and guns are particularly configured for feeding fired shell casings back into the linkless magazine from which the shells are fed.
Known linkless conveyor-type shell magazines are typically configured for storing several hundred shells. As a result, the fully-loaded shell conveyors usually weigh many hundreds of pounds and, therefore, have considerable inertial resistance to start-up movement, thus making high instantaneous firing rates of the associated gun difficult to attain.
In some weapons systems utilizing linkless conveyor magazines, the high start-up inertial resistance of the loaded conveyor is overcome by use of high conveyor driving power. Because more power is required to provide rapid acceleration of the loaded conveyor from rest than is required to drive the conveyor once the conveyor is up to speed, the power source must, in such systems, be much greater than is otherwise necessary. This, in turn, causes system size, weight and power consumption to be increased. Moreover, the application of very high driving forces to the conveyor, to enable fast start-up movement, subjects parts of the magazine and conveyor to stresses which may reduce operational life and reliability of the magazines. To withstand such stresses, size and/or weight of the magazine may have to be increased, further adding to system size and weight.
As an alternative to providing such high start-up driving forces, some types of linkless conveyor magazines provide means whereby, during start up, only a few shells are advanced towards the associated shell feeder. These few shells are rapidly advanced while movement of the entire conveyor is less rapidly brought up to its full, shell-transferring velocity. As a result, the necessity for increased, conveyor driving power to accelerate the conveyor at a high rate upon initiation of firing is eliminated.
Heretofore to Applicant's knowledge, such apparatus enabling advancing of only a few shells at the initiating of firing have been relatively complex, and have hence been heavy, expensive and of questionable reliability and/or have not been particularly effective.
An object of the present invention is, therefore, to provide, for a linkless shell magazine having an endless-loop shell conveyor apparatus which enables, in response to start-up driving of the shell conveyor, just that segment of the conveyor immediately upstream adjacent to the shell transfer position, which contains only a few shells, to move before the rest of the conveyor starts moving, thereby enabling a high start-up firing rate.
Another object of the present invention is to provide, for a linkless shell magazine having an endless-loop shell conveyor, apparatus which enables instantaneous and temporary driving isolation, upon conveyor drive start-up, of a small segment of the conveyor which passes by a magazine shell transfer position, the rest of the conveyor being driven up to speed while shells are being fed to the gun from the first driven segment of the conveyor.
A further object of the present invention is to provide guiding for an endless-loop shell conveyor of a linkless shell magazine so that, upon conveyor driving start-up, only a short segment of the conveyor just upstream of a magazine shell transfer position is caused to be driven towards the transfer position before further upstream segments of the conveyor start moving.
Other objects, features and advantages of the present invention wll be readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.